Devices for recycling expired anesthetic are known from the state of the art and are based on the principle that expired gas is sent over a filter, which adsorbs expired anesthetic and fresh breathing gas is sent subsequently over the filter during a desorption phase in order to enrich it with previously stored anesthetic.
A device of this class is known from U.S. Pat. No. 6,206,002 B1. A patient is connected via a breathing gas line to a filter device for adsorbing and desorbing anesthetic. Fresh breathing gas arrives now at the patient from a breathing gas source via the filter device and a breathing gas line. The breathing gas is mixed with anesthetic by means of an anesthetic source in the vicinity of the patient. The anesthetic breathed out by the patient is adsorbed in the filter device during the phase of expiration and mixed again with the gas to be breathed in during the next inspiration stroke. The anesthetic consumed by the patient during stationary operation and the anesthetic not adsorbed by the filter device during the phase of expiration are replaced with the anesthetic source. Anesthetic is mixed with the breathing gas in the liquid form during the phase of expiration, and only special anesthetic dispensing devices can therefore be used. The dispensing of liquid anesthetic in the vicinity of the patient requires a great effort in terms of monitoring of the release of concentration.
EP 1 440 704 B1 discloses a device for the recycling of anesthetic, in which an adsorption filter is moved between two gas channels in order to alternatingly expose a same section of the filter to the interior of each channel. Since separate channels are present in this device for the gas to be breathed in and the expired gas, the dead space volume decreases to the volume of the filter sections that are staggered between the gas channels. However, more specific data on how the anesthetic is fed to the patient cannot be found in the document. It is also disadvantageous in the prior-art device that a rinsing gas is needed during a rapid phase of termination in order to rinse through the adsorption beds and to remove the anesthetic.